<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"><head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JavaScript下拉菜单演示代码</title>
<style type="text/css">
body {margin:25px; font:12px Verdana, Arial, Helvetica}
* {padding:0; margin:0}
.dropdown {float:left; padding-right:0px}
.dropdown dt {width:80px; border:2px solid #9ac1c9; padding:8px; font-weight:bold; cursor:pointer; background:url()}
.dropdown dt:hover {background:url()}
.dropdown dd {position:absolute; overflow:hidden; width:100px; display:none; background:#fff; z-index:200; opacity:0}
.dropdown ul {width:100px; border:2px solid #9ac1c9; list-style:none; border-top:none}
.dropdown li {display:inline}
.dropdown a, .dropdown a:active, .dropdown a:visited {display:block; padding:5px; color:#333; text-decoration:none; background:#eaf0f2; width:194px}
.dropdown a:hover {background:#d9e1e4; color:#000}
.dropdown .underline {border-bottom:1px solid #b9d6dc}
</style>
<script language="javascript">
var DDSPEED = 10;
var DDTIMER = 15;
function ddMenu(id,d){
		var h = document.getElementById(id + '-ddheader');
		var c = document.getElementById(id + '-ddcontent');
		clearInterval(c.timer);
		if(d == 1){
				clearTimeout(h.timer);
				if(c.maxh && c.maxh <= c.offsetHeight){return}
				else if(!c.maxh){
						c.style.display = 'block';
						c.style.height = 'auto';
						c.maxh = c.offsetHeight;
						c.style.height = '0px';
				}
				c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
		}else{
				h.timer = setTimeout(function(){ddCollapse(c)},50);
		}
}

// collapse the menu //
function ddCollapse(c){
		c.timer = setInterval(function(){ddSlide(c,-1)},DDTIMER);
}
function cancelHide(id){
		var h = document.getElementById(id + '-ddheader');
		var c = document.getElementById(id + '-ddcontent');
		clearTimeout(h.timer);
		clearInterval(c.timer);
		if(c.offsetHeight < c.maxh){
				c.timer = setInterval(function(){ddSlide(c,1)},DDTIMER);
		}
}
function ddSlide(c,d){
		var currh = c.offsetHeight;
		var dist;
		if(d == 1){
				dist = (Math.round((c.maxh - currh) / DDSPEED));
		}else{
				dist = (Math.round(currh / DDSPEED));
		}
		if(dist <= 1 && d == 1){
				dist = 1;
		}
		c.style.height = currh + (dist * d) + 'px';
		c.style.opacity = currh / c.maxh;
		c.style.filter = 'alpha(opacity=' + (currh * 100 / c.maxh) + ')';
						if((currh < 2 && d != 1) || (currh > (c.maxh - 2) && d == 1)){
						clearInterval(c.timer);
						}
						}
						</script>
						</head>
						<body>
						<br><br>

						<dl class="dropdown">
						<dt id="one-ddheader" onmouseover="ddMenu('one',1)" onmouseout="ddMenu('one',-1)">One</dt>

						<dd id="one-ddcontent" onmouseover="cancelHide('one')" onmouseout="ddMenu('one',-1)">
						<ul>
						<li><a href="http://www.codefans.net/" class="underline">源码爱好者</a></li>
						<li><a href="#" class="underline">Navigation Item 2</a></li>
						<li><a href="#" class="underline">Navigation Item 3</a></li>
						<li><a href="#" class="underline">Navigation Item 4</a></li>
						<li><a href="#">Navigation Item 5</a></li>

		</ul>
		</dd>
		</dl>

		<dl class="dropdown">
		<dt id="two-ddheader" onmouseover="ddMenu('two',1)" onmouseout="ddMenu('two',-1)">Two</dt>
		<dd id="two-ddcontent" onmouseover="cancelHide('two')" onmouseout="ddMenu('two',-1)">
		<ul>
		<li><a href="#" class="underline">Navigation Item 1</a></li>

		<li><a href="#" class="underline">Navigation Item 2</a></li>
		<li><a href="#" class="underline">Navigation Item 3</a></li>
		<li><a href="http://www.baidu.com/" class="underline">默认主页</a></li>
		<li><a href="#">Navigation Item 5</a></li>
		</ul>
		</dd>
		</dl>

		<dl class="dropdown">
		<dt id="three-ddheader" onmouseover="ddMenu('three',1)" onmouseout="ddMenu('three',-1)">Two</dt>
		<dd id="three-ddcontent" onmouseover="cancelHide('three')" onmouseout="ddMenu('three',-1)">
		<ul>
		<li><a href="#" class="underline">Navigation Item 1</a></li>
		<li><a href="#" class="underline">Navigation Item 2</a></li>
		<li><a href="#" class="underline">Navigation Item 3</a></li>

		<li><a href="#" class="underline">Navigation Item 4</a></li>
		<li><a href="#">Navigation Item 5</a></li>
		</ul>
		</dd>
		</dl>

		<dl class="dropdown">
		<dt id="four-ddheader" onmouseover="ddMenu('four',1)" onmouseout="ddMenu('four',-1)">Two</dt>
		<dd id="four-ddcontent" onmouseover="cancelHide('four')" onmouseout="ddMenu('four',-1)">

		<ul>
		<li><a href="http://www.baidu.com/" class="underline">默认主页</a></li>
		<li><a href="#" class="underline">Navigation Item 2</a></li>
		<li><a href="#" class="underline">Navigation Item 3</a></li>
		<li><a href="#" class="underline">Navigation Item 4</a></li>
		<li><a href="#">Navigation Item 5</a></li>

		</ul>
		</dd>
		</dl>

		<dl class="dropdown">
		<dt id="fir-ddheader" onmouseover="ddMenu('fir',1)" onmouseout="ddMenu('fir',-1)">Two</dt>
		<dd id="fir-ddcontent" onmouseover="cancelHide('fir')" onmouseout="ddMenu('fir',-1)">
		<ul>
		<li><a href="#" class="underline">Navigation Item 1</a></li>

		<li><a href="http://www.baidu.com/" class="underline">默认主页</a></li>
		<li><a href="#" class="underline">Navigation Item 3</a></li>
		<li><a href="#" class="underline">Navigation Item 4</a></li>
		<li><a href="#">Navigation Item 5</a></li>
		</ul>
		</dd>
		</dl>

		<dl class="dropdown">
		<dt id="six-ddheader" onmouseover="ddMenu('six',1)" onmouseout="ddMenu('six',-1)">Two</dt>
		<dd id="six-ddcontent" onmouseover="cancelHide('six')" onmouseout="ddMenu('six',-1)">
		<ul>
		<li><a href="#" class="underline">Navigation Item 1</a></li>
		<li><a href="#" class="underline">Navigation Item 2</a></li>
		<li><a href="#" class="underline">Navigation Item 3</a></li>

		<li><a href="#" class="underline">Navigation Item 4</a></li>
		<li><a href="#">Navigation Item 5</a></li>
		</ul>
		</dd>
		</dl>

		<dl class="dropdown">
		<dt id="seven-ddheader" onmouseover="ddMenu('seven',1)" onmouseout="ddMenu('seven',-1)">Two</dt>
		<dd id="seven-ddcontent" onmouseover="cancelHide('seven')" onmouseout="ddMenu('seven',-1)">

		<ul>
		<li><a href="#" class="underline">Navigat</a></li>
		<li><a href="#" class="underline">Naviga</a></li>
		<li><a href="#" class="underline">Navigati</a></li>
		<li><a href="#" class="underline">Navigat</a></li>
		<li><a href="#">Navigatio</a></li>
		</ul>
		</dd>
		</dl>
		<div style="clear:both">
		</div>
</body>
</html>